The Sloan Digital Sky Survey has recently discovered a coherent ring of stars at low galactic latitude that is believed to be the tidal stream of a merging dwarf galaxy in the Galactic plane (named the Monoceros tidal stream). The existence and location of the core of its progenitor galaxy is still controversial. The best candidate is the Canis Major dwarf galaxy, a distinct overdensity of red stars discovered in the 2MASS survey, but also interpreted as the signature of the Galactic warp viewed in projection. In this paper, we report a variety of new observational evidence that supports the notion that CMa is the remnant of a partially disrupted core of a dwarf satellite. The comparison of the orbit derived from our theoretical model for the parent galaxy of this ring-like structure with an accurate determination of CMa orbit leads to the conclusion that this satellite is the best candidate for the progenitor of the Monoceros tidal stream

HI 21cm absorption spectroscopy provides an independent probe of the nature of damped Lyman-$\alpha$ systems (DLAs), yielding information on their ISM conditions, kinematics, and spatial extent. We find that the majority of DLAs have significantly higher spin temperatures than seen in the Milky Way and local spirals, indicating larger fractions of the warm phase of HI, especially at high redshifts. Present data suggests that the spin temperature might be used as a secondary indicator of the nature of the absorbing galaxy. We have succeeded in spatially resolving the 21cm absorption in two $z\sim 0.4$ DLAs, thus obtaining lower limits on the transverse extent of these absorbers.

Cataclysmic variables (CVs) formed through close encounters may be the most abundant class of compact binaries in globular clusters. As part of a systematic search for CVs undergoing dwarf nova eruptions (DN) in globular clusters, our 2004 monitoring program of M22 detected an outburst of a CV candidate during May. We present a light curve for the May 2004 period, obtained using the ISIS image subtraction routine. Our ground based results are in good agreement with previous HST measurements, and confirm the DN nature of the outburst and the object's CV status. Further application of the ISIS software will enable us to identify other DN candidates in the core of M22 with the aim of characterizing the properties of these systems, as opposed to similar ones in the field.

We present the results of a study of some selected spectral regions, including those around the LiI lines at 6708 Å and 6104 Å in the magnetic chemically peculiar star HD 3980 and in a few other Ap stars with different effective temperatures and different strengths of the magnetic field. High resolution spectroscopic observations were carried out with the Coudé echelle spectrograph at the 74-inch telescope of the Mount Stromlo Observatory ($R=88000$) and with the VLT UV-Visual Echelle Spectrograph UVES at UT2 at ESO ($R=110000$). Using spectral synthesis we determined abundances of Li, Ce, Pr, Nd and some other rare earth elements and showed that the spectral feature at 6708 Å in the spectrum of HD 3980 is due to the Li I doublet with only a minor contribution of the Ce II line at 6708.099 Å.

We investigate the problem of giant planet formation around stars with various masses based on the core accretion/gas capture model. At first, we follow the evolution of gas and solids from the moment when all solids are in the form of small grains to the stage when most of them have reached planetesimal size. We show that the surface density of a planetesimal swarm tends to be higher around less massive stars. Subsequently, we derive the minimum surface density of the planetesimal swarm required for the formation of giant planets, both in a numerical and in an approximate analytical approach. We combine these results by calculating a set of representative disk models, characterized by different masses, sizes, and metallicities. This allows us to quantify the probability of each individual disk model to form giant planets. Furthermore, we take the fact into account, that in some of these models, the outer regions of the disks become gravitationally unstable.

We report an on-going blank-field multi-wavelength deep and wide survey of the Subaru/XMM-Newton Deep Survey Field (SXDF). The SXDF has been the focus of a wide range of multi-wavelength observing programs spanning the X-ray to the radio. These observations cover a large enough area (the initial optical imaging covers $\sim$1.3 deg$^{2}$) and depth ($B=28.2$) that they are not affected by large-scale structures (which exist on tens of Mpc scales) and allow us to study the distribution and evolution of high-$z$ galaxies and AGNs, and thus constrain theories for their formation. Our early results include: i) an indication of the primeval Large Scale Structure (LSS) at z $\sim$ 5.7, ii) an indication for the down-sizing of galaxy formation at z $\sim$ 1, iii) identifications of passively evolving systems, and evidence for early formation and the passive evolution of present-day early-type galaxies, and iv) discovery of a large number of optically obscured QSOs. As for the next step forward - we express our hope to use the next generation optical/IR Extremely Large Telescopes (ELTs) to obtain larger and deeper spectroscopy samples of the high-$z$ objects.

IR imaging, K–band spectroscopy and X-ray data of the stellar cluster in M 17 suggests three categories of massive young objects: I) “Naked” early-type O-stars in the cluster center that exhibit X-ray emission and normal optical/IR-spectra; they do not show signs for any circumstellar material. II) Late O-type stars, that show X-ray emission and H/He absorption lines in their optical/IR-spectra. There is evidence for extended circumstellar material in the form of elongated L–band nebulae, circumstellar MIR emission from regions of about 10.000 AU in diameter and filaments of He I $1.083\,\mu$m. III) Massive stars without X-ray emission, K–band spectra with emission lines of H and He and in some cases with CO band head emission. They are heavily enshrouded and also show elongated L–band nebulae, circumstellar MIR emission from regions of about 4.000 AU and ionized He envelopes.

Obviously, M 17 harbors several generations of massive stars: Only the oldest “Category I”, located in the cluster center, is free of circumstellar material. “Category II” and “III” comprise younger dust-enshrouded objects of a second generation embedded in the interface of the HII region and the adjacent molecular cloud. Due to the presence of flattened dusty disks and perpendicular gaseous outflows, accretion seems to be important for the formation of stars up to type O8.

A population of X-ray emitting sources with($L_{\rm bol} \sim 10^4\,$L$_\odot$) shows CO band head absorption; one source was found to have variable CO absorption as known from FU Orionis stars.

New data on the 20.000 AU accretion disk in M 17 reveals a collimated H$_2$$2.122\,\mu$m jet with three distinct emission knots that emerges from the disk center. The broad H$\alpha$ and Ca II emission lines from the bipolar nebula display blue-shifted absorption originating from accretion disk-driven outflows with velocities of $\pm 500$ km/s.

An asteroid family is a group of asteroids with similar orbits and spectra that was produced by a collisional breakup of a large parent body. To identify asteroid families, researchers look for clusters of asteroid positions in the space of proper orbital elements. These elements, being more constant over time than osculating orbital elements, provide a dynamical criterion of whether a group of bodies has a common ancestor. More than fifty asteroid families have been identified to date. Their analysis produced several important insights into the physics of large scale collisions, dynamical processes affecting small bodies in the Solar System, and surface and interior properties of asteroids.

This report is a brief summary of some of the major achievements in studies of planets and satellites that have been accomplished during the years 2003–2005. Unlike previous years, we do not attempt to provide a detailed overview of the field but rather choose to highlight aspects which are of particular novelty.

We report the first astronomical detection of the CF$^+$ (fluoromethylidynium) ion, obtained by recent observations of its $J = 1-0$ (102.6 GHz), $J = 2-1$ (205.2 GHz), and $J = 3-2$ (307.7 GHz) pure rotational emissions toward the Orion Bar. Our search for CF$^+$ — carried out using the IRAM 30m and APEX 12m telescopes—was motivated by recent theoretical models that predict CF$^+$ abundances of a $\rm few \times 10^{-10}$ in UV-irradiated molecular regions where C$^+$ is present. The measurements confirm the predictions. They provide support for our current theories of interstellar fluorine chemistry, which suggest that hydrogen fluoride should be ubiquitous in interstellar gas clouds.

The next generation of high-contrast imaging instruments will provide the first unresolved image of an extrasolar planet. While the emitted infrared light from the planet in thermal equilibrium should show almost no phase effect, the reflected visible light will vary with the orbital phase angle. We study the photometric variation of the reflected light with orbital phase of a ringed extrasolar planet. We show that a ring around an extrasolar planet, both obviously unresolved, can be detected by its specific photometric signature.

We report on the use of high-resolution spectra to obtain a detailed description of the Sagittarius dwarf spheroidal internal dynamics, its Mass and Mass to Light ratio (M/L). Our direct measure of the central velocity dispersion of SGR give $\sigma_{SGR}=8.1\pm0.4$ km/s which translates in a total mass estimate of $M_{SGR} =1.6\times10^8 M_{\odot}$ and corresponding $(M/L)_{SGR}=9.1 (M/L)_{\odot}$. We also report on a possible detection of rotation in the core of SGR.

The past triennium has continued to see a huge influx of astrometric positions of small solar system bodies provided by near-Earth object (NEO) surveys. As a result, the size of the orbital databases of all populations of small solar system bodies continues to increase dramatically, and this in turn allows finer and finer analyses of the types of motion in various regions of the orbital elements space.

We combine FUV spectra obtained with FUSE and STIS/E140M of HE 0226–4116 ($z=0.495$), PG 1116+215 ($z_{\rm em}=0.177$), and PG 1259+593 ($z_{\rm em}=0.478$) to determine the distribution of column density and Doppler width of the Ly$\alpha$ absorber population at $z<0.5$ detected in the spectra of these 3 quasars. The high spectral resolution UV spectra allow us to derive simultaneously the redshift, column density, and Doppler width of each absorber. Two different populations of H I absorbers appear to be present: narrow and broad H I absorptions that could be tracers of the warm photoionised IGM ($T < 10^5$ K) and warm-hot ionised medium (WHIM, $T \sim 10^5-10^6$ K). For a reliable assessment of the baryonic content of the Ly$\alpha$ forest at low $z$ it is crucial to determine the relative numbers of photoionised absorbers vs. hot collisionally ionised absorbers. Preliminary results indicate that 30–40% of the total baryons are in the photoionised IGM and at least 20% in the WHIM. We also discuss the observed evolution of the Doppler parameter with redshift.

In the past several years, great progress has been made on the spectroscopy of polyatomic molecules in diffuse interstellar clouds. In this talk, I will review recent developments involving H$_3^+$, C$_3$, and the Diffuse Interstellar Bands (DIBs).

The simplest polyatomic molecular ion, H$_3^+$, has long been recognized as the cornerstone of ion-neutral chemistry in dense molecular clouds (Herbst & Klemperer 1973; Watson 1973). However, in diffuse clouds (where electrons are abundantly produced from photoionization of atomic carbon) the H$_3^+$ number density was expected to be considerably lower than in dense clouds, owing to the efficiency of electron recombination. It was, therefore, a surprise when a large column density of H$_3^+$ was detected (McCall et al.1998) in the diffuse line of sight towards Cygnus OB2 12, and subsequently in a sample of heavily reddened diffuse sightlines (McCall et al.2002). Recently, we have detected H$_3^+$ even in the classical diffuse cloud sightline towards $\zeta$ Persei; together with a new measurement of the electron recombination rate coefficient, this result suggests that the cosmic-ray ionization rate is much higher in diffuse clouds than in dense clouds (McCall et al. 2003a)!

In 2001, interstellar C$_3$ was first detected by J. P. Maier and colleagues (maier et al. 2001) in three diffuse cloud sightlines. This was quickly followed up by another detection (Roueff et al. 2002) and a survey conducted at low-resolution (Okaet al. 2003). This was followed by a high-resolution survey (Ádámkovics, Blake, & McCall 2003) that yielded rotationally resolved spectra of C$_3$ in 10 sightlines. Much like C$_2$, C$_3$ has no permanent dipole moment, and therefore its rotational distribution serves as a sensitive diagnostic of both temperature and density.

The existence of larger polyatomic molecules in diffuse clouds is clear from the presence of the DIBs, which have remained an enigma since their discovery some eight decades ago. A recent survey of the DIBs at the Apache Point Observatory has resulted in a uniform sample of DIB spectra with much higher signal-to-noise ratios than previously available. Some early results from the analysis of the survey data include the identification of a set of DIBs that are related to C$_2$ (Thorburn et al. 2003) as well as some well-correlated pairs of DIBs. I will discuss our recent results.

The discovery of binaries in each of the major populations of minor bodies in the solar system is propelling a rapid growth of heretofore unattainable physical information. The availability of mass and density constraints for minor bodies opens the door to studies of internal structure, comparisons with meteorite samples, and correlations between bulk-physical and surface-spectral properties. The number of known binaries is now more than 70 and is growing rapidly. A smaller number have had the extensive followup observations needed to derive mass and albedo information, but this list is growing as well. It will soon be the case that we will know more about the physical parameters of objects in the Kuiper Belt than has been known about asteroids in the Main Belt for the last 200 years. Another important aspect of binaries is understanding the mechanisms that lead to their formation and survival. The relative sizes and separations of binaries in the different minor body populations point to more than one mechanism for forming bound pairs. Collisions appear to play a major role in the Main Belt. Rotational and/or tidal fission may be important in the Near Earth population. For the Kuiper Belt, capture in multi-body interactions may be the preferred formation mechanism. However, all of these conclusions remain tentative and limited by observational and theoretical incompleteness. Observational techniques for identifying binaries are equally varied. High angular resolution observations from space and from the ground are critical for detection of the relatively distant binaries in the Main Belt and the Kuiper Belt. Radar has been the most productive method for detection of Near Earth binaries. Lightcurve analysis is an independent technique that is capable of exploring phase space inaccessible to direct observations. Finally, spacecraft flybys have played a crucial paradigm-changing role with discoveries that unlocked this now-burgeoning field.

We started (sub-)millimeter continuum and line studies of entire molecular cloud complexes located at intermediate distances from the Sun (1–3 kpc). Such an unbiased approach allows to identify and characterize the earliest phases of high-mass stars overlooked by IRAS or MSX. Our complete MAMBO-2 surveys of the Cygnus X and NGC 7538 complexes reveal a large population of ${\sim} 0.1$ pc-size massive young stellar objects (MYSOs) harboring high-mass infrared-quiet protostars. The determination of the nature of all the new millimeter sources is still in progress but we have already collected evidence that the infrared-quiet (or class 0-like) protostellar phase might last as long as the better-known infrared-bright protostellar phase. Besides, our complete census of MYSOs fails to discover the high-mass analogues of pre-stellar dense cores. We propose that the observed lower-density pre-stellar clumps (${>} 1$ pc) rapidly concentrate and collapse as also found in the kinematical studies of other prominent clumps. Indeed, CS and HCO$^+$ mappings in W43 and Cygnus X suggest global supersonic contraction with inward velocities of several km s−1 on parsec scales. Our work and similar studies of entire star-forming complexes will thus definitively contribute to a better knowledge of the earliest phases of high-mass star formation.

A highlight science case for the European ELT is: First light - The First Galaxies and the Ionization State of the Early Universe. It aims at understanding the formation and evolution of the first sources of light at the end of the Dark Ages and of the re-ionization of the Universe. The corresponding instrument requirements are: a few tens of integral field units with spatial sampling $\sim$20mas and individual fields of ${\sim}1''$ over a wide field of view of $5' \times 5'$ or larger. Multi-Object Adaptive Optics is required to locally provide significant image quality enhancement. Spectroscopic observations are required in the near IR domain with a spectral resolution of a few 1000. MOMFIS is a preliminary instrument concept designed for OWL around this science case. The instrument concept and preliminary design are presented. Development efforts are estimated, as well as development risks and required R&D activities.

We present results from a high resolution study of six Li-depleted halo dwarfs. These stars exhibit Lithium abundances more than 0.5 dex below the Spite Plateau. The study is comprised of two parts: 1) a detailed abundance analysis covering many light, alpha, Fe-peak and neutron capture elements and 2) a study of rotational line broadening. We find that there are no common abundance anomalies, other than the Lithium depletion, that distinguish these stars from the Li-normal population. Four of the six stars however, show evidence of abnormally high projected rotation velocities. These findings support a non-standard depletion mechanism in Li-depleted halo stars, and emphasize their necessary exclusion from future studies of the Spite Plateau.

We present a new analysis of the light curve of the secondary star in the PSR B1957+20 system. Combining previous data and new data points at minimum from the Hubble Space Telescope, we have 100% coverage in the R-band. We also have a number of new K$_s$ band data points, which we use to constrain the IR magnitude of the system. We model this with the Eclipsing Light Curve code. From the modeling we obtain colour information about the secondary at minimum in BVRI & K. For our best fit model we are able to constrain the system inclination to 66.6 $\pm$ 2.1$^o$ for pulsar masses ranging from 1.35 – 1.9 M$_{\odot}$. The pulsar mass is unconstrained. We also find that the secondary is not filling its Roche lobe, which has important consequences for evolutionary models of this system. The temperature of the un-irradiated side of the companion is in agreement with previous estimates.